The production of hydrogen peroxide by cathodic reduction of oxygen in an aqueous electrolyte is known as is the use of special electrodes, electrode materials and electrode compositions as the cathode in such processes for the production of hydrogen peroxide. In general, the oxygen required for reduction is introduced into contact with the aqueous phase, i.e. the electrolyte, through the permeable electrode which can have, as the active electrode material, an activated carbon in which a conductive network, e.g. a grid, is embedded. Furthermore, to prevent complete wetting of the active material and saturation of the interstices thereof with the electrolyte, the active mass may include a hydrophobic material such as polytetrafluoroethylene.
The reaction is deemed to occur at the three-phase interface formed by the gas, the aqueous electrolyte and the solid material of the electrode. The cathodic current is supplied by the conductive grid which is embedded in the active mass.
It is known from German open application (Offenlegungsschrift) 23 53 259 and U.S. Pat. No. 3,968,273 to produce electrodes of this type, especially for use in the electrolytic production of hydrogen peroxide, by heating activated-carbon powder in a vacuum to incandescence at temperatures above 900.degree. C. This process is thought to create a surface structure of the activated carbon which promotes the generation of the hydrogen peroxide. Possible impurities on the active surface of the active carbon are eliminated by physical desorption in the vacuum used during the incandescent heating.
This process has, however, the disadvantage that long incandescent heating times are required to obtain the optimum surface structure and characteristics necessary for effective production of the hydrogen peroxide. Naturally, since the reaction vessel must remain under high vacuum during these prolonged periods, the construction thereof must take this fact into consideration. As a result, the vessel is placed under high stresses and frequently must be inspected, repaired and maintained, or must be constructed and dimensioned, at high cost, to avoid such maintenance and operating expenditures. As a practical matter, the high vacuum cannot be maintained for such long periods in a reasonable and effective manner.